Effect of calcination temperature on the performance of hexaaluminate supported CeO2 for chemical looping dry reforming

The chemical looping dry reforming (CLDR) of methane is a novel syngas production and CO2 utilization technology via the circulation of oxygen carrier. In this work, BaFe3Al9O19 (BF3) hexaaluminate supported CeO2 serves as oxygen carrier for CLDR. Combined with a series of characterization, the effect of interaction between CeO2 and hexaaluminate as a function of calcination temperatures (700, 800, 900 and 1000 °C) on the CLDR performance was carefully investigated, and then the possible reaction mechanism was proposed. The results show that fresh CeO2/BF3 is composed of CeO2, β-Al2O3 and magnetoplumite (MP) hexaaluminate. Increasing the calcination temperature from 700 to 900 °C is conducive to enhancing the interaction strength between CeO2 and hexaaluminate, which favors the diffusion of lattice oxygen to the surface. However, 1000 °C calcination leads to the sintering of oxygen carrier, which hinders the migration of lattice oxygen. Among CeO2/BF3-T (T = 700–1000 °C), CeO2/BF3–900 °C presents not only a high methane conversion (~85%), high syngas yield (1.28–2.02 mmol/g) with ideal H2/CO ratio (~2), but also excellent CO2 activation ability and cyclic stability in the periodic CH4/CO2 redox cycles. The results were mainly attributed to the highest concentration of Ce3+ and Fe2+, abundant oxygen vacancies and the formation of CeFexAl1-xO3.